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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group. Adapted and released, under explicit permission, |
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* from JDK ArrayList.java which carries the following copyright: |
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* |
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* Copyright 1997 by Sun Microsystems, Inc., |
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* 901 San Antonio Road, Palo Alto, California, 94303, U.S.A. |
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* All rights reserved. |
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* |
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* This software is the confidential and proprietary information |
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* of Sun Microsystems, Inc. ("Confidential Information"). You |
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* shall not disclose such Confidential Information and shall use |
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* it only in accordance with the terms of the license agreement |
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* you entered into with Sun. |
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*/ |
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|
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package java.util.concurrent; |
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import java.util.*; |
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|
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/** |
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* A thread-safe variant of {@link java.util.ArrayList} in which all mutative |
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* operations (<tt>add</tt>, <tt>set</tt>, and so on) are implemented by |
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* making a fresh copy of the underlying array. |
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* |
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* <p> This is ordinarily too costly, but may be <em>more</em> efficient |
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* than alternatives when traversal operations vastly outnumber |
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* mutations, and is useful when you cannot or don't want to |
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* synchronize traversals, yet need to preclude interference among |
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* concurrent threads. The "snapshot" style iterator method uses a |
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* reference to the state of the array at the point that the iterator |
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* was created. This array never changes during the lifetime of the |
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* iterator, so interference is impossible and the iterator is |
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* guaranteed not to throw <tt>ConcurrentModificationException</tt>. |
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* The iterator will not reflect additions, removals, or changes to |
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* the list since the iterator was created. Element-changing |
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* operations on iterators themselves (<tt>remove</tt>, <tt>set</tt>, and |
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* <tt>add</tt>) are not supported. These methods throw |
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* <tt>UnsupportedOperationException</tt>. |
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* |
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* <p>All elements are permitted, including <tt>null</tt>. |
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* |
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* <p>This class is a member of the |
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* <a href="{@docRoot}/../guide/collections/index.html"> |
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* Java Collections Framework</a>. |
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* |
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* @since 1.5 |
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* @author Doug Lea |
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* @param <E> the type of elements held in this collection |
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*/ |
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public class CopyOnWriteArrayList<E> |
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implements List<E>, RandomAccess, Cloneable, java.io.Serializable { |
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private static final long serialVersionUID = 8673264195747942595L; |
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|
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/** The array, accessed only via getArray/setArray. */ |
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private volatile transient E[] array; |
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|
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private E[] getArray() { return array; } |
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private void setArray(E[] a) { array = a; } |
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|
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/** |
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* Creates an empty list. |
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*/ |
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public CopyOnWriteArrayList() { |
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setArray((E[]) new Object[0]); |
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} |
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|
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/** |
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* Creates a list containing the elements of the specified |
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* collection, in the order they are returned by the collection's |
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* iterator. |
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* |
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* @param c the collection of initially held elements |
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* @throws NullPointerException if the specified collection is null |
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*/ |
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public CopyOnWriteArrayList(Collection<? extends E> c) { |
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E[] elements = (E[]) new Object[c.size()]; |
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int size = 0; |
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for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) |
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elements[size++] = i.next(); |
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setArray(elements); |
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} |
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|
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/** |
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* Creates a list holding a copy of the given array. |
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* |
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* @param toCopyIn the array (a copy of this array is used as the |
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* internal array) |
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* @throws NullPointerException if the specified array is null |
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*/ |
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public CopyOnWriteArrayList(E[] toCopyIn) { |
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copyIn(toCopyIn, 0, toCopyIn.length); |
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} |
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|
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/** |
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* Replaces the held array with a copy of the <tt>n</tt> elements |
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* of the provided array, starting at position <tt>first</tt>. To |
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* copy an entire array, call with arguments (array, 0, |
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* array.length). |
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* @param toCopyIn the array. A copy of the indicated elements of |
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* this array is used as the internal array. |
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* @param first The index of first position of the array to |
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* start copying from. |
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* @param n the number of elements to copy. This will be the new size of |
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* the list. |
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*/ |
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private synchronized void copyIn(E[] toCopyIn, int first, int n) { |
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int limit = first + n; |
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if (limit > toCopyIn.length) |
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throw new IndexOutOfBoundsException(); |
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setArray((E[]) cloneRange(toCopyIn, first, limit, Object[].class)); |
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} |
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|
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/** |
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* Returns the number of elements in this list. |
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* |
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* @return the number of elements in this list |
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*/ |
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public int size() { |
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return getArray().length; |
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} |
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|
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/** |
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* Returns <tt>true</tt> if this list contains no elements. |
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* |
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* @return <tt>true</tt> if this list contains no elements |
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*/ |
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public boolean isEmpty() { |
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return size() == 0; |
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} |
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|
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/** |
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* static version of indexOf, to allow repeated calls without |
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* needing to grab re-acquire array each time. |
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* @param o element to search for |
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* @param elements the array |
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* @param index first index to search |
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* @param fence one past last index to search |
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* @return index of element, or -1 if absent |
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*/ |
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private static int indexOf(Object o, Object[] elements, |
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int index, int fence) { |
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if (o == null) { |
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for (int i = index; i < fence; i++) |
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if (elements[i] == null) |
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return i; |
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} else { |
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for (int i = index; i < fence; i++) |
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if (o.equals(elements[i])) |
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return i; |
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} |
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return -1; |
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} |
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|
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/** |
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* static version of lastIndexOf. |
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* @param o element to search for |
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* @param elements the array |
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* @param index first index to search |
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* @return index of element, or -1 if absent |
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*/ |
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private static int lastIndexOf(Object o, Object[] elements, int index) { |
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if (o == null) { |
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for (int i = index; i >= 0; i--) |
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if (elements[i] == null) |
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return i; |
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} else { |
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for (int i = index; i >= 0; i--) |
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if (o.equals(elements[i])) |
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return i; |
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} |
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return -1; |
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} |
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|
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/** |
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* Returns <tt>true</tt> if this list contains the specified element. |
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* More formally, returns <tt>true</tt> if and only if this list contains |
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* at least one element <tt>e</tt> such that |
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* <tt>(o==null ? e==null : o.equals(e))</tt>. |
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* |
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* @param o element whose presence in this list is to be tested |
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* @return <tt>true</tt> if this list contains the specified element |
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*/ |
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public boolean contains(Object o) { |
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E[] elements = getArray(); |
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return indexOf(o, elements, 0, elements.length) >= 0; |
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} |
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|
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/** |
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* {@inheritDoc} |
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*/ |
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public int indexOf(Object o) { |
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E[] elements = getArray(); |
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return indexOf(o, elements, 0, elements.length); |
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} |
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|
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|
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/** |
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* Returns the index of the first occurrence of the specified element in |
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* this list, searching forwards from <tt>index</tt>, or returns -1 if |
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* the element is not found. |
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* More formally, returns the lowest index <tt>i</tt> such that |
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* <tt>(i >= index && (e==null ? get(i)==null : e.equals(get(i))))</tt>, |
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* or -1 if there is no such index. |
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* |
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* @param e element to search for |
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* @param index index to start searching from |
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* @return the index of the first occurrence of the element in |
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* this list at position <tt>index</tt> or later in the list; |
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* <tt>-1</tt> if the element is not found. |
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* @throws IndexOutOfBoundsException if the specified index is negative |
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*/ |
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public int indexOf(E e, int index) { |
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E[] elements = getArray(); |
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return indexOf(e, elements, index, elements.length); |
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} |
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|
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/** |
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* {@inheritDoc} |
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*/ |
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public int lastIndexOf(Object o) { |
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E[] elements = getArray(); |
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return lastIndexOf(o, elements, elements.length - 1); |
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} |
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|
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/** |
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* Returns the index of the last occurrence of the specified element in |
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* this list, searching backwards from <tt>index</tt>, or returns -1 if |
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* the element is not found. |
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* More formally, returns the highest index <tt>i</tt> such that |
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* <tt>(i <= index && (e==null ? get(i)==null : e.equals(get(i))))</tt>, |
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* or -1 if there is no such index. |
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* |
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* @param e element to search for |
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* @param index index to start searching backwards from |
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* @return the index of the last occurrence of the element at position |
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* less than or equal to <tt>index</tt> in this list; |
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* -1 if the element is not found. |
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* @throws IndexOutOfBoundsException if the specified index is greater |
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* than or equal to the current size of this list |
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*/ |
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public int lastIndexOf(E e, int index) { |
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E[] elements = getArray(); |
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return lastIndexOf(e, elements, index); |
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} |
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|
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/** |
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* Returns a shallow copy of this list. (The elements themselves |
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* are not copied.) |
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* |
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* @return a clone of this list |
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*/ |
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public Object clone() { |
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try { |
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E[] elements = getArray(); |
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CopyOnWriteArrayList<E> v = (CopyOnWriteArrayList<E>)super.clone(); |
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v.setArray(clone(elements, elements.length)); |
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return v; |
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} catch (CloneNotSupportedException e) { |
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// this shouldn't happen, since we are Cloneable |
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throw new InternalError(); |
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} |
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} |
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|
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/** |
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* Returns an array containing all of the elements in this list |
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* in proper sequence (from first to last element). |
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* |
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* <p>The returned array will be "safe" in that no references to it are |
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* maintained by this list. (In other words, this method must allocate |
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* a new array). The caller is thus free to modify the returned array. |
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* |
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* <p>This method acts as bridge between array-based and collection-based |
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* APIs. |
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* |
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* @return an array containing all the elements in this list |
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*/ |
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public Object[] toArray() { |
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Object[] elements = getArray(); |
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return clone(elements, elements.length); |
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} |
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|
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/** |
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* Returns an array containing all of the elements in this list in |
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* proper sequence (from first to last element); the runtime type of |
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* the returned array is that of the specified array. If the list fits |
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* in the specified array, it is returned therein. Otherwise, a new |
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* array is allocated with the runtime type of the specified array and |
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* the size of this list. |
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* |
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* <p>If this list fits in the specified array with room to spare |
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* (i.e., the array has more elements than this list), the element in |
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* the array immediately following the end of the list is set to |
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* <tt>null</tt>. (This is useful in determining the length of this |
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* list <i>only</i> if the caller knows that this list does not contain |
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* any null elements.) |
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* |
297 |
* <p>Like the {@link #toArray()} method, this method acts as bridge between |
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* array-based and collection-based APIs. Further, this method allows |
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* precise control over the runtime type of the output array, and may, |
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* under certain circumstances, be used to save allocation costs. |
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* |
302 |
* <p>Suppose <tt>x</tt> is a list known to contain only strings. |
303 |
* The following code can be used to dump the list into a newly |
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* allocated array of <tt>String</tt>: |
305 |
* |
306 |
* <pre> |
307 |
* String[] y = x.toArray(new String[0]);</pre> |
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* |
309 |
* Note that <tt>toArray(new Object[0])</tt> is identical in function to |
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* <tt>toArray()</tt>. |
311 |
* |
312 |
* @param a the array into which the elements of the list are to |
313 |
* be stored, if it is big enough; otherwise, a new array of the |
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* same runtime type is allocated for this purpose. |
315 |
* @return an array containing all the elements in this list |
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* @throws ArrayStoreException if the runtime type of the specified array |
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* is not a supertype of the runtime type of every element in |
318 |
* this list |
319 |
* @throws NullPointerException if the specified array is null |
320 |
*/ |
321 |
public <T> T[] toArray(T a[]) { |
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E[] elements = getArray(); |
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int len = elements.length; |
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if (a.length < len) |
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return (T[]) clone(elements, len, a.getClass()); |
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else { |
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System.arraycopy(elements, 0, a, 0, len); |
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if (a.length > len) |
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a[len] = null; |
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return a; |
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} |
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} |
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|
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// Positional Access Operations |
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|
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/** |
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* {@inheritDoc} |
338 |
* |
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* @throws IndexOutOfBoundsException {@inheritDoc} |
340 |
*/ |
341 |
public E get(int index) { |
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return getArray()[index]; |
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} |
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|
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/** |
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* Replaces the element at the specified position in this list with the |
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* specified element. |
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* |
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* @throws IndexOutOfBoundsException {@inheritDoc} |
350 |
*/ |
351 |
public synchronized E set(int index, E element) { |
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E[] elements = getArray(); |
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int len = elements.length; |
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E oldValue = elements[index]; |
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|
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if (oldValue != element && |
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(element == null || !element.equals(oldValue))) { |
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E[] newElements = clone(elements, len); |
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newElements[index] = element; |
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setArray(newElements); |
361 |
} |
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return oldValue; |
363 |
} |
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|
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/** |
366 |
* Appends the specified element to the end of this list. |
367 |
* |
368 |
* @param e element to be appended to this list |
369 |
* @return <tt>true</tt> (as per the spec for {@link Collection#add}) |
370 |
*/ |
371 |
public synchronized boolean add(E e) { |
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E[] elements = getArray(); |
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int len = elements.length; |
374 |
E[] newElements = clone(elements, len + 1); |
375 |
newElements[len] = e; |
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setArray(newElements); |
377 |
return true; |
378 |
} |
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|
380 |
/** |
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* Inserts the specified element at the specified position in this |
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* list. Shifts the element currently at that position (if any) and |
383 |
* any subsequent elements to the right (adds one to their indices). |
384 |
* |
385 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
386 |
*/ |
387 |
public synchronized void add(int index, E element) { |
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E[] elements = getArray(); |
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int len = elements.length; |
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if (index > len || index < 0) |
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throw new IndexOutOfBoundsException("Index: " + index+ |
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", Size: " + len); |
393 |
E[] newElements; |
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int numMoved = len - index; |
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if (numMoved == 0) |
396 |
newElements = clone(elements, len + 1); |
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else { |
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newElements = (E[]) new Object[len + 1]; |
399 |
System.arraycopy(elements, 0, newElements, 0, index); |
400 |
System.arraycopy(elements, index, newElements, index + 1, |
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numMoved); |
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} |
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newElements[index] = element; |
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setArray(newElements); |
405 |
} |
406 |
|
407 |
/** |
408 |
* Removes the element at the specified position in this list. |
409 |
* Shifts any subsequent elements to the left (subtracts one from their |
410 |
* indices). Returns the element that was removed from the list. |
411 |
* |
412 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
413 |
*/ |
414 |
public synchronized E remove(int index) { |
415 |
E[] elements = getArray(); |
416 |
int len = elements.length; |
417 |
E oldValue = elements[index]; |
418 |
int numMoved = len - index - 1; |
419 |
if (numMoved == 0) |
420 |
setArray(clone(elements, len - 1)); |
421 |
else { |
422 |
E[] newElements = (E[]) new Object[len - 1]; |
423 |
System.arraycopy(elements, 0, newElements, 0, index); |
424 |
System.arraycopy(elements, index + 1, newElements, index, |
425 |
numMoved); |
426 |
setArray(newElements); |
427 |
} |
428 |
return oldValue; |
429 |
} |
430 |
|
431 |
/** |
432 |
* Removes the first occurrence of the specified element from this list, |
433 |
* if it is present. If this list does not contain the element, it is |
434 |
* unchanged. More formally, removes the element with the lowest index |
435 |
* <tt>i</tt> such that |
436 |
* <tt>(o==null ? get(i)==null : o.equals(get(i)))</tt> |
437 |
* (if such an element exists). Returns <tt>true</tt> if this list |
438 |
* contained the specified element (or equivalently, if this list |
439 |
* changed as a result of the call). |
440 |
* |
441 |
* @param o element to be removed from this list, if present |
442 |
* @return <tt>true</tt> if this list contained the specified element |
443 |
*/ |
444 |
public synchronized boolean remove(Object o) { |
445 |
E[] elements = getArray(); |
446 |
int len = elements.length; |
447 |
if (len != 0) { |
448 |
// Copy while searching for element to remove |
449 |
// This wins in the normal case of element being present |
450 |
int newlen = len - 1; |
451 |
E[] newElements = (E[]) new Object[newlen]; |
452 |
|
453 |
for (int i = 0; i < newlen; ++i) { |
454 |
if (o == elements[i] || |
455 |
(o != null && o.equals(elements[i]))) { |
456 |
// found one; copy remaining and exit |
457 |
for (int k = i + 1; k < len; ++k) |
458 |
newElements[k - 1] = elements[k]; |
459 |
setArray(newElements); |
460 |
return true; |
461 |
} else |
462 |
newElements[i] = elements[i]; |
463 |
} |
464 |
|
465 |
// special handling for last cell |
466 |
if (o == elements[newlen] || |
467 |
(o != null && o.equals(elements[newlen]))) { |
468 |
setArray(newElements); |
469 |
return true; |
470 |
} |
471 |
} |
472 |
return false; |
473 |
} |
474 |
|
475 |
/** |
476 |
* Removes from this list all of the elements whose index is between |
477 |
* <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive. |
478 |
* Shifts any succeeding elements to the left (reduces their index). |
479 |
* This call shortens the list by <tt>(toIndex - fromIndex)</tt> elements. |
480 |
* (If <tt>toIndex==fromIndex</tt>, this operation has no effect.) |
481 |
* |
482 |
* @param fromIndex index of first element to be removed |
483 |
* @param toIndex index after last element to be removed |
484 |
* @throws IndexOutOfBoundsException if fromIndex or toIndex out of |
485 |
* range (fromIndex < 0 || fromIndex >= size() || toIndex |
486 |
* > size() || toIndex < fromIndex) |
487 |
*/ |
488 |
private synchronized void removeRange(int fromIndex, int toIndex) { |
489 |
E[] elements = getArray(); |
490 |
int len = elements.length; |
491 |
|
492 |
if (fromIndex < 0 || fromIndex >= len || |
493 |
toIndex > len || toIndex < fromIndex) |
494 |
throw new IndexOutOfBoundsException(); |
495 |
int newlen = len - (toIndex - fromIndex); |
496 |
int numMoved = len - toIndex; |
497 |
if (numMoved == 0) |
498 |
setArray(clone(elements, newlen)); |
499 |
else { |
500 |
E[] newElements = (E[]) new Object[newlen]; |
501 |
System.arraycopy(elements, 0, newElements, 0, fromIndex); |
502 |
System.arraycopy(elements, toIndex, newElements, |
503 |
fromIndex, numMoved); |
504 |
setArray(newElements); |
505 |
} |
506 |
} |
507 |
|
508 |
/** |
509 |
* Append the element if not present. |
510 |
* |
511 |
* @param e element to be added to this list, if absent |
512 |
* @return <tt>true</tt> if the element was added |
513 |
*/ |
514 |
public synchronized boolean addIfAbsent(E e) { |
515 |
// Copy while checking if already present. |
516 |
// This wins in the most common case where it is not present |
517 |
E[] elements = getArray(); |
518 |
int len = elements.length; |
519 |
E[] newElements = (E[]) new Object[len + 1]; |
520 |
for (int i = 0; i < len; ++i) { |
521 |
if (e == elements[i] || (e != null && e.equals(elements[i]))) |
522 |
return false; // exit, throwing away copy |
523 |
else |
524 |
newElements[i] = elements[i]; |
525 |
} |
526 |
newElements[len] = e; |
527 |
setArray(newElements); |
528 |
return true; |
529 |
} |
530 |
|
531 |
/** |
532 |
* Returns <tt>true</tt> if this list contains all of the elements of the |
533 |
* specified collection. |
534 |
* |
535 |
* @param c collection to be checked for containment in this list |
536 |
* @return <tt>true</tt> if this list contains all of the elements of the |
537 |
* specified collection |
538 |
* @throws NullPointerException if the specified collection is null |
539 |
* @see #contains(Object) |
540 |
*/ |
541 |
public boolean containsAll(Collection<?> c) { |
542 |
E[] elements = getArray(); |
543 |
int len = elements.length; |
544 |
for (Iterator e = c.iterator(); e.hasNext(); ) { |
545 |
if (indexOf(e.next(), elements, 0, len) < 0) |
546 |
return false; |
547 |
} |
548 |
return true; |
549 |
} |
550 |
|
551 |
/** |
552 |
* Removes from this list all of its elements that are contained in |
553 |
* the specified collection. This is a particularly expensive operation |
554 |
* in this class because of the need for an internal temporary array. |
555 |
* |
556 |
* @param c collection containing elements to be removed from this list |
557 |
* @return <tt>true</tt> if this list changed as a result of the call |
558 |
* @throws ClassCastException if the class of an element of this list |
559 |
* is incompatible with the specified collection (optional) |
560 |
* @throws NullPointerException if this list contains a null element and the |
561 |
* specified collection does not permit null elements (optional), |
562 |
* or if the specified collection is null |
563 |
* @see #remove(Object) |
564 |
*/ |
565 |
public synchronized boolean removeAll(Collection<?> c) { |
566 |
E[] elements = getArray(); |
567 |
int len = elements.length; |
568 |
if (len != 0) { |
569 |
// temp array holds those elements we know we want to keep |
570 |
int newlen = 0; |
571 |
E[] temp = (E[]) new Object[len]; |
572 |
for (int i = 0; i < len; ++i) { |
573 |
E element = elements[i]; |
574 |
if (!c.contains(element)) |
575 |
temp[newlen++] = element; |
576 |
} |
577 |
if (newlen != len) { |
578 |
setArray((E[])cloneRange(temp, 0, newlen, Object[].class)); |
579 |
return true; |
580 |
} |
581 |
} |
582 |
return false; |
583 |
} |
584 |
|
585 |
/** |
586 |
* Retains only the elements in this list that are contained in the |
587 |
* specified collection. In other words, removes from this list all of |
588 |
* its elements that are not contained in the specified collection. |
589 |
* |
590 |
* @param c collection containing elements to be retained in this list |
591 |
* @return <tt>true</tt> if this list changed as a result of the call |
592 |
* @throws ClassCastException if the class of an element of this list |
593 |
* is incompatible with the specified collection (optional) |
594 |
* @throws NullPointerException if this list contains a null element and the |
595 |
* specified collection does not permit null elements (optional), |
596 |
* or if the specified collection is null |
597 |
* @see #remove(Object) |
598 |
*/ |
599 |
public synchronized boolean retainAll(Collection<?> c) { |
600 |
E[] elements = getArray(); |
601 |
int len = elements.length; |
602 |
if (len != 0) { |
603 |
int newlen = 0; |
604 |
E[] temp = (E[]) new Object[len]; |
605 |
for (int i = 0; i < len; ++i) { |
606 |
E element = elements[i]; |
607 |
if (c.contains(element)) |
608 |
temp[newlen++] = element; |
609 |
} |
610 |
if (newlen != len) { |
611 |
setArray((E[])cloneRange(temp, 0, newlen, Object[].class)); |
612 |
return true; |
613 |
} |
614 |
} |
615 |
return false; |
616 |
} |
617 |
|
618 |
/** |
619 |
* Appends all of the elements in the specified collection that |
620 |
* are not already contained in this list, to the end of |
621 |
* this list, in the order that they are returned by the |
622 |
* specified collection's iterator. |
623 |
* |
624 |
* @param c collection containing elements to be added to this list |
625 |
* @return the number of elements added |
626 |
* @throws NullPointerException if the specified collection is null |
627 |
* @see #addIfAbsent(Object) |
628 |
*/ |
629 |
public synchronized int addAllAbsent(Collection<? extends E> c) { |
630 |
int added = 0; |
631 |
int numNew = c.size(); |
632 |
if (numNew != 0) { |
633 |
E[] elements = getArray(); |
634 |
int len = elements.length; |
635 |
|
636 |
E[] temp = (E[]) new Object[numNew]; |
637 |
for (Iterator<? extends E> e = c.iterator(); e.hasNext(); ) { |
638 |
E element = e.next(); |
639 |
if (indexOf(element, elements, 0, len) < 0 && |
640 |
indexOf(element, temp, 0, added) < 0) |
641 |
temp[added++] = element; |
642 |
} |
643 |
if (added != 0) { |
644 |
E[] newElements = (E[]) new Object[len + added]; |
645 |
System.arraycopy(elements, 0, newElements, 0, len); |
646 |
System.arraycopy(temp, 0, newElements, len, added); |
647 |
setArray(newElements); |
648 |
} |
649 |
} |
650 |
return added; |
651 |
} |
652 |
|
653 |
/** |
654 |
* Removes all of the elements from this list. |
655 |
* The list will be empty after this call returns. |
656 |
*/ |
657 |
public synchronized void clear() { |
658 |
setArray((E[]) new Object[0]); |
659 |
} |
660 |
|
661 |
/** |
662 |
* Appends all of the elements in the specified collection to the end |
663 |
* of this list, in the order that they are returned by the specified |
664 |
* collection's iterator. |
665 |
* |
666 |
* @param c collection containing elements to be added to this list |
667 |
* @return <tt>true</tt> if this list changed as a result of the call |
668 |
* @throws NullPointerException if the specified collection is null |
669 |
* @see #add(Object) |
670 |
*/ |
671 |
public synchronized boolean addAll(Collection<? extends E> c) { |
672 |
int numNew = c.size(); |
673 |
if (numNew == 0) |
674 |
return false; |
675 |
|
676 |
E[] elements = getArray(); |
677 |
int len = elements.length; |
678 |
E[] newElements = (E[]) new Object[len + numNew]; |
679 |
System.arraycopy(elements, 0, newElements, 0, len); |
680 |
Iterator<? extends E> e = c.iterator(); |
681 |
for (int i = 0; i < numNew; i++) |
682 |
newElements[len++] = e.next(); |
683 |
setArray(newElements); |
684 |
return true; |
685 |
} |
686 |
|
687 |
/** |
688 |
* Inserts all of the elements in the specified collection into this |
689 |
* list, starting at the specified position. Shifts the element |
690 |
* currently at that position (if any) and any subsequent elements to |
691 |
* the right (increases their indices). The new elements will appear |
692 |
* in this list in the order that they are returned by the |
693 |
* specified collection's iterator. |
694 |
* |
695 |
* @param index index at which to insert the first element |
696 |
* from the specified collection |
697 |
* @param c collection containing elements to be added to this list |
698 |
* @return <tt>true</tt> if this list changed as a result of the call |
699 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
700 |
* @throws NullPointerException if the specified collection is null |
701 |
* @see #add(int,Object) |
702 |
*/ |
703 |
public synchronized boolean addAll(int index, Collection<? extends E> c) { |
704 |
E[] elements = getArray(); |
705 |
int len = elements.length; |
706 |
if (index > len || index < 0) |
707 |
throw new IndexOutOfBoundsException("Index: " + index + |
708 |
", Size: "+ len); |
709 |
int numNew = c.size(); |
710 |
if (numNew == 0) |
711 |
return false; |
712 |
int numMoved = len - index; |
713 |
E[] newElements; |
714 |
if (numMoved == 0) |
715 |
newElements = clone(elements, len + numNew); |
716 |
else { |
717 |
newElements = (E[]) new Object[len + numNew]; |
718 |
System.arraycopy(elements, index, newElements, |
719 |
index + numNew, numMoved); |
720 |
System.arraycopy(elements, index, newElements, |
721 |
index + numNew, numMoved); |
722 |
} |
723 |
Iterator<? extends E> e = c.iterator(); |
724 |
for (int i = 0; i < numNew; i++) |
725 |
newElements[index++] = e.next(); |
726 |
setArray(newElements); |
727 |
|
728 |
return true; |
729 |
} |
730 |
|
731 |
/** |
732 |
* Save the state of the list to a stream (i.e., serialize it). |
733 |
* |
734 |
* @serialData The length of the array backing the list is emitted |
735 |
* (int), followed by all of its elements (each an Object) |
736 |
* in the proper order. |
737 |
* @param s the stream |
738 |
*/ |
739 |
private void writeObject(java.io.ObjectOutputStream s) |
740 |
throws java.io.IOException{ |
741 |
|
742 |
// Write out element count, and any hidden stuff |
743 |
s.defaultWriteObject(); |
744 |
|
745 |
E[] elements = getArray(); |
746 |
int len = elements.length; |
747 |
// Write out array length |
748 |
s.writeInt(len); |
749 |
|
750 |
// Write out all elements in the proper order. |
751 |
for (int i = 0; i < len; i++) |
752 |
s.writeObject(elements[i]); |
753 |
} |
754 |
|
755 |
/** |
756 |
* Reconstitute the list from a stream (i.e., deserialize it). |
757 |
* @param s the stream |
758 |
*/ |
759 |
private void readObject(java.io.ObjectInputStream s) |
760 |
throws java.io.IOException, ClassNotFoundException { |
761 |
|
762 |
// Read in size, and any hidden stuff |
763 |
s.defaultReadObject(); |
764 |
|
765 |
// Read in array length and allocate array |
766 |
int len = s.readInt(); |
767 |
E[] elements = (E[]) new Object[len]; |
768 |
|
769 |
// Read in all elements in the proper order. |
770 |
for (int i = 0; i < len; i++) |
771 |
elements[i] = (E) s.readObject(); |
772 |
setArray(elements); |
773 |
} |
774 |
|
775 |
/** |
776 |
* Returns a string representation of this list, containing |
777 |
* the String representation of each element. |
778 |
*/ |
779 |
public String toString() { |
780 |
E[] elements = getArray(); |
781 |
int maxIndex = elements.length - 1; |
782 |
StringBuffer buf = new StringBuffer(); |
783 |
buf.append("["); |
784 |
for (int i = 0; i <= maxIndex; i++) { |
785 |
buf.append(String.valueOf(elements[i])); |
786 |
if (i < maxIndex) |
787 |
buf.append(", "); |
788 |
} |
789 |
buf.append("]"); |
790 |
return buf.toString(); |
791 |
} |
792 |
|
793 |
/** |
794 |
* Compares the specified object with this list for equality. |
795 |
* Returns true if and only if the specified object is also a {@link |
796 |
* List}, both lists have the same size, and all corresponding pairs |
797 |
* of elements in the two lists are <em>equal</em>. (Two elements |
798 |
* <tt>e1</tt> and <tt>e2</tt> are <em>equal</em> if <tt>(e1==null ? |
799 |
* e2==null : e1.equals(e2))</tt>.) In other words, two lists are |
800 |
* defined to be equal if they contain the same elements in the same |
801 |
* order. |
802 |
* |
803 |
* @param o the object to be compared for equality with this list |
804 |
* @return <tt>true</tt> if the specified object is equal to this list |
805 |
*/ |
806 |
public boolean equals(Object o) { |
807 |
if (o == this) |
808 |
return true; |
809 |
if (!(o instanceof List)) |
810 |
return false; |
811 |
|
812 |
List<E> l2 = (List<E>)(o); |
813 |
if (size() != l2.size()) |
814 |
return false; |
815 |
|
816 |
ListIterator<E> e1 = listIterator(); |
817 |
ListIterator<E> e2 = l2.listIterator(); |
818 |
while (e1.hasNext()) { |
819 |
E o1 = e1.next(); |
820 |
E o2 = e2.next(); |
821 |
if (!(o1 == null ? o2 == null : o1.equals(o2))) |
822 |
return false; |
823 |
} |
824 |
return true; |
825 |
} |
826 |
|
827 |
/** |
828 |
* Returns the hash code value for this list. |
829 |
* |
830 |
* <p> This implementation uses the definition in {@link |
831 |
* List#hashCode}. |
832 |
* @return the hash code |
833 |
*/ |
834 |
public int hashCode() { |
835 |
int hashCode = 1; |
836 |
E[] elements = getArray(); |
837 |
int len = elements.length; |
838 |
for (int i = 0; i < len; ++i) { |
839 |
E obj = elements[i]; |
840 |
hashCode = 31 * hashCode + (obj == null ? 0 : obj.hashCode()); |
841 |
} |
842 |
return hashCode; |
843 |
} |
844 |
|
845 |
/** |
846 |
* Returns an iterator over the elements in this list in proper sequence. |
847 |
* |
848 |
* <p>The returned iterator provides a snapshot of the state of the list |
849 |
* when the iterator was constructed. No synchronization is needed while |
850 |
* traversing the iterator. The iterator does <em>NOT</em> support the |
851 |
* <tt>remove</tt> method. |
852 |
* |
853 |
* @return an iterator over the elements in this list in proper sequence |
854 |
*/ |
855 |
public Iterator<E> iterator() { |
856 |
return new COWIterator<E>(getArray(), 0); |
857 |
} |
858 |
|
859 |
/** |
860 |
* {@inheritDoc} |
861 |
* |
862 |
* <p>The returned iterator provides a snapshot of the state of the list |
863 |
* when the iterator was constructed. No synchronization is needed while |
864 |
* traversing the iterator. The iterator does <em>NOT</em> support the |
865 |
* <tt>remove</tt>, <tt>set</tt> or <tt>add</tt> methods. |
866 |
*/ |
867 |
public ListIterator<E> listIterator() { |
868 |
return new COWIterator<E>(getArray(), 0); |
869 |
} |
870 |
|
871 |
/** |
872 |
* {@inheritDoc} |
873 |
* |
874 |
* <p>The list iterator returned by this implementation will throw an |
875 |
* <tt>UnsupportedOperationException</tt> in its <tt>remove</tt>, |
876 |
* <tt>set</tt> and <tt>add</tt> methods. |
877 |
* |
878 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
879 |
*/ |
880 |
public ListIterator<E> listIterator(final int index) { |
881 |
E[] elements = getArray(); |
882 |
int len = elements.length; |
883 |
if (index < 0 || index > len) |
884 |
throw new IndexOutOfBoundsException("Index: " + index); |
885 |
|
886 |
return new COWIterator<E>(getArray(), index); |
887 |
} |
888 |
|
889 |
private static class COWIterator<E> implements ListIterator<E> { |
890 |
/** Snapshot of the array **/ |
891 |
private final E[] snapshot; |
892 |
/** Index of element to be returned by subsequent call to next. */ |
893 |
private int cursor; |
894 |
|
895 |
private COWIterator(E[] elements, int initialCursor) { |
896 |
cursor = initialCursor; |
897 |
snapshot = elements; |
898 |
} |
899 |
|
900 |
public boolean hasNext() { |
901 |
return cursor < snapshot.length; |
902 |
} |
903 |
|
904 |
public boolean hasPrevious() { |
905 |
return cursor > 0; |
906 |
} |
907 |
|
908 |
public E next() { |
909 |
try { |
910 |
return snapshot[cursor++]; |
911 |
} catch (IndexOutOfBoundsException ex) { |
912 |
throw new NoSuchElementException(); |
913 |
} |
914 |
} |
915 |
|
916 |
public E previous() { |
917 |
try { |
918 |
return snapshot[--cursor]; |
919 |
} catch (IndexOutOfBoundsException e) { |
920 |
throw new NoSuchElementException(); |
921 |
} |
922 |
} |
923 |
|
924 |
public int nextIndex() { |
925 |
return cursor; |
926 |
} |
927 |
|
928 |
public int previousIndex() { |
929 |
return cursor - 1; |
930 |
} |
931 |
|
932 |
/** |
933 |
* Not supported. Always throws UnsupportedOperationException. |
934 |
* @throws UnsupportedOperationException always; <tt>remove</tt> |
935 |
* is not supported by this iterator. |
936 |
*/ |
937 |
public void remove() { |
938 |
throw new UnsupportedOperationException(); |
939 |
} |
940 |
|
941 |
/** |
942 |
* Not supported. Always throws UnsupportedOperationException. |
943 |
* @throws UnsupportedOperationException always; <tt>set</tt> |
944 |
* is not supported by this iterator. |
945 |
*/ |
946 |
public void set(E e) { |
947 |
throw new UnsupportedOperationException(); |
948 |
} |
949 |
|
950 |
/** |
951 |
* Not supported. Always throws UnsupportedOperationException. |
952 |
* @throws UnsupportedOperationException always; <tt>add</tt> |
953 |
* is not supported by this iterator. |
954 |
*/ |
955 |
public void add(E e) { |
956 |
throw new UnsupportedOperationException(); |
957 |
} |
958 |
} |
959 |
|
960 |
/** |
961 |
* Returns a view of the portion of this list between |
962 |
* <tt>fromIndex</tt>, inclusive, and <tt>toIndex</tt>, exclusive. |
963 |
* The returned list is backed by this list, so changes in the |
964 |
* returned list are reflected in this list, and vice-versa. |
965 |
* While mutative operations are supported, they are probably not |
966 |
* very useful for CopyOnWriteArrayLists. |
967 |
* |
968 |
* <p>The semantics of the list returned by this method become |
969 |
* undefined if the backing list (i.e., this list) is |
970 |
* <i>structurally modified</i> in any way other than via the |
971 |
* returned list. (Structural modifications are those that change |
972 |
* the size of the list, or otherwise perturb it in such a fashion |
973 |
* that iterations in progress may yield incorrect results.) |
974 |
* |
975 |
* @param fromIndex low endpoint (inclusive) of the subList |
976 |
* @param toIndex high endpoint (exclusive) of the subList |
977 |
* @return a view of the specified range within this list |
978 |
* @throws IndexOutOfBoundsException {@inheritDoc} |
979 |
*/ |
980 |
public synchronized List<E> subList(int fromIndex, int toIndex) { |
981 |
// synchronized since sublist constructor depends on it. |
982 |
E[] elements = getArray(); |
983 |
int len = elements.length; |
984 |
if (fromIndex < 0 || toIndex > len || fromIndex > toIndex) |
985 |
throw new IndexOutOfBoundsException(); |
986 |
return new COWSubList<E>(this, fromIndex, toIndex); |
987 |
} |
988 |
|
989 |
private static class COWSubList<E> extends AbstractList<E> { |
990 |
/* |
991 |
This class extends AbstractList merely for convenience, to |
992 |
avoid having to define addAll, etc. This doesn't hurt, but |
993 |
is wasteful. This class does not need or use modCount |
994 |
mechanics in AbstractList, but does need to check for |
995 |
concurrent modification using similar mechanics. On each |
996 |
operation, the array that we expect the backing list to use |
997 |
is checked and updated. Since we do this for all of the |
998 |
base operations invoked by those defined in AbstractList, |
999 |
all is well. While inefficient, this is not worth |
1000 |
improving. The kinds of list operations inherited from |
1001 |
AbstractList are already so slow on COW sublists that |
1002 |
adding a bit more space/time doesn't seem even noticeable. |
1003 |
*/ |
1004 |
|
1005 |
private final CopyOnWriteArrayList<E> l; |
1006 |
private final int offset; |
1007 |
private int size; |
1008 |
private E[] expectedArray; |
1009 |
|
1010 |
private COWSubList(CopyOnWriteArrayList<E> list, |
1011 |
int fromIndex, int toIndex) { |
1012 |
l = list; |
1013 |
expectedArray = l.getArray(); |
1014 |
offset = fromIndex; |
1015 |
size = toIndex - fromIndex; |
1016 |
} |
1017 |
|
1018 |
// only call this holding l's lock |
1019 |
private void checkForComodification() { |
1020 |
if (l.getArray() != expectedArray) |
1021 |
throw new ConcurrentModificationException(); |
1022 |
} |
1023 |
|
1024 |
// only call this holding l's lock |
1025 |
private void rangeCheck(int index) { |
1026 |
if (index < 0 || index >= size) |
1027 |
throw new IndexOutOfBoundsException("Index: " + index + |
1028 |
",Size: " + size); |
1029 |
} |
1030 |
|
1031 |
public E set(int index, E element) { |
1032 |
synchronized(l) { |
1033 |
rangeCheck(index); |
1034 |
checkForComodification(); |
1035 |
E x = l.set(index + offset, element); |
1036 |
expectedArray = l.getArray(); |
1037 |
return x; |
1038 |
} |
1039 |
} |
1040 |
|
1041 |
public E get(int index) { |
1042 |
synchronized(l) { |
1043 |
rangeCheck(index); |
1044 |
checkForComodification(); |
1045 |
return l.get(index + offset); |
1046 |
} |
1047 |
} |
1048 |
|
1049 |
public int size() { |
1050 |
synchronized(l) { |
1051 |
checkForComodification(); |
1052 |
return size; |
1053 |
} |
1054 |
} |
1055 |
|
1056 |
public void add(int index, E element) { |
1057 |
synchronized(l) { |
1058 |
checkForComodification(); |
1059 |
if (index<0 || index>size) |
1060 |
throw new IndexOutOfBoundsException(); |
1061 |
l.add(index + offset, element); |
1062 |
expectedArray = l.getArray(); |
1063 |
size++; |
1064 |
} |
1065 |
} |
1066 |
|
1067 |
public void clear() { |
1068 |
synchronized(l) { |
1069 |
checkForComodification(); |
1070 |
l.removeRange(offset, offset+size); |
1071 |
expectedArray = l.getArray(); |
1072 |
size = 0; |
1073 |
} |
1074 |
} |
1075 |
|
1076 |
public E remove(int index) { |
1077 |
synchronized(l) { |
1078 |
rangeCheck(index); |
1079 |
checkForComodification(); |
1080 |
E result = l.remove(index + offset); |
1081 |
expectedArray = l.getArray(); |
1082 |
size--; |
1083 |
return result; |
1084 |
} |
1085 |
} |
1086 |
|
1087 |
public Iterator<E> iterator() { |
1088 |
synchronized(l) { |
1089 |
checkForComodification(); |
1090 |
return new COWSubListIterator<E>(l, 0, offset, size); |
1091 |
} |
1092 |
} |
1093 |
|
1094 |
public ListIterator<E> listIterator(final int index) { |
1095 |
synchronized(l) { |
1096 |
checkForComodification(); |
1097 |
if (index<0 || index>size) |
1098 |
throw new IndexOutOfBoundsException("Index: "+index+ |
1099 |
", Size: "+size); |
1100 |
return new COWSubListIterator<E>(l, index, offset, size); |
1101 |
} |
1102 |
} |
1103 |
|
1104 |
public List<E> subList(int fromIndex, int toIndex) { |
1105 |
synchronized(l) { |
1106 |
checkForComodification(); |
1107 |
if (fromIndex<0 || toIndex>size) |
1108 |
throw new IndexOutOfBoundsException(); |
1109 |
return new COWSubList<E>(l, fromIndex + offset, |
1110 |
toIndex + offset); |
1111 |
} |
1112 |
} |
1113 |
|
1114 |
} |
1115 |
|
1116 |
|
1117 |
private static class COWSubListIterator<E> implements ListIterator<E> { |
1118 |
private final ListIterator<E> i; |
1119 |
private final int index; |
1120 |
private final int offset; |
1121 |
private final int size; |
1122 |
private COWSubListIterator(List<E> l, int index, int offset, |
1123 |
int size) { |
1124 |
this.index = index; |
1125 |
this.offset = offset; |
1126 |
this.size = size; |
1127 |
i = l.listIterator(index + offset); |
1128 |
} |
1129 |
|
1130 |
public boolean hasNext() { |
1131 |
return nextIndex() < size; |
1132 |
} |
1133 |
|
1134 |
public E next() { |
1135 |
if (hasNext()) |
1136 |
return i.next(); |
1137 |
else |
1138 |
throw new NoSuchElementException(); |
1139 |
} |
1140 |
|
1141 |
public boolean hasPrevious() { |
1142 |
return previousIndex() >= 0; |
1143 |
} |
1144 |
|
1145 |
public E previous() { |
1146 |
if (hasPrevious()) |
1147 |
return i.previous(); |
1148 |
else |
1149 |
throw new NoSuchElementException(); |
1150 |
} |
1151 |
|
1152 |
public int nextIndex() { |
1153 |
return i.nextIndex() - offset; |
1154 |
} |
1155 |
|
1156 |
public int previousIndex() { |
1157 |
return i.previousIndex() - offset; |
1158 |
} |
1159 |
|
1160 |
public void remove() { |
1161 |
throw new UnsupportedOperationException(); |
1162 |
} |
1163 |
|
1164 |
public void set(E e) { |
1165 |
throw new UnsupportedOperationException(); |
1166 |
} |
1167 |
|
1168 |
public void add(E e) { |
1169 |
throw new UnsupportedOperationException(); |
1170 |
} |
1171 |
} |
1172 |
|
1173 |
// Temporary emulations of anticipated new j.u.Arrays functions |
1174 |
|
1175 |
private static <T,U> T[] cloneRange(U[] original, int from, int to, |
1176 |
Class<? extends T[]> newType) { |
1177 |
int newLength = to - from; |
1178 |
if (newLength < 0) |
1179 |
throw new IllegalArgumentException(from + " > " + to); |
1180 |
T[] copy = (T[]) java.lang.reflect.Array.newInstance |
1181 |
(newType.getComponentType(), newLength); |
1182 |
System.arraycopy(original, from, copy, 0, |
1183 |
Math.min(original.length - from, newLength)); |
1184 |
return copy; |
1185 |
} |
1186 |
|
1187 |
private static <T,U> T[] clone(U[] original, int newLength, |
1188 |
Class<? extends T[]> newType) { |
1189 |
T[] copy = (T[]) java.lang.reflect.Array.newInstance |
1190 |
(newType.getComponentType(), newLength); |
1191 |
System.arraycopy(original, 0, copy, 0, |
1192 |
Math.min(original.length, newLength)); |
1193 |
return copy; |
1194 |
} |
1195 |
|
1196 |
private static <T> T[] clone(T[] original, int newLength) { |
1197 |
return (T[]) clone(original, newLength, original.getClass()); |
1198 |
} |
1199 |
|
1200 |
} |